For hard disk drives, performance improvement of both heads and drive media (magnetic substances) have been advanced, and hard disk drives having higher capacity and smaller size have been developed.
From the viewpoint of the performance improvement of media drives, the drives having higher capacity have been developed by increasing surface recording densities. In the increase in the recording density, a magnetic field spreads at a magnetic head. To solve this problem, a smaller magnetic head has been developed, which has a limitation. Such magnetic field spreading does not become smaller than a certain value, and thus a phenomenon called “side write” occurs. When the side write occurs, writing to adjacent tracks occurs during recording. This causes data elimination by overwriting an already recorded data. The magnetic field spreading also causes reading of extra signals from the adjacent tracks during playing, and this generates cross talk.
In order to solve these disadvantages, technologies such as discreet track media and bit patterned media, in which tracks are physically and magnetically separated by filling gaps between the tracks with a non-magnetic material, have been proposed (Patent Document 1).
Filling of a non-magnetic material between tracks is performed by applying a film-forming composition including the non-magnetic material onto a magnetic layer having projections and recesses formed on a substrate and carrying out etch back to the surface of the magnetic layer using dry etching to form a plane at which a magnetic layer and a non-magnetic layer are leveled. This non-magnetic layer is in contact with the magnetic layer at a bottom part and a side part and the magnetic material may diffuse from the magnetic layer to the non-magnetic layer. A polysiloxane-based material is used for preventing the diffusion (Patent Document 2).